Electronystagmograph control system

ABSTRACT

An electronystagmograph including a system for irrigating the subject&#39;&#39;s ear with hot or cold water to cause nystagmus, sensors for measuring the potential in the vicinity of the subject&#39;&#39;s eyes, 2-channel recording means, and a timing system for controlling a valve in the water supply for establishing the irrigation interval and energizing one recording channel to record the duration of the irrigation interval and, at the end of the irrigation interval, to energize the second channel to record the potential detected by the sensors during a subsequent measuring interval.

United States Patent Inventors Behrman A. Ducote Richardson;

Lawrence V. Nicastro, Irving, Tex. 802,753

Feb. 19, 1969 Continuation of Ser. No. 586,508, 921. 3 i e Feb. 16, 1971Tracor Inc.

Austin, Tex.

a corporation of Tercas Appl. No. Filed Patented AssigneeELECTRONYSTAGMOGRAPH CONTROL SYSTEM 5 Claims, 1 Drawing Fig.

U.S. Cl 128/21 Int. Cl A611) 5/10 Field of Search 128/2, 2 1

[56] References Citedl UNITED STATES PATENTS 2,902,030 9/1959 Kennedy etal. l28/2.1 3,000,271 9/1961 Harvey et a1... 128/21 3,029,808 4/1962Kagan 128/2.1X 3,217,706 11/1965 Sullivan 128/21 PrimaryExaminer-William E. Kamm Attorney-Arnold, Roylance, Kruger and DurkesABSTRACT: An electronystagmograph including a system for irrigating thesubject's ear with hot or cold water to cause nystagmus, sensors formeasuring the potential inthe vicinity of the subjects eyes, Z-channelrecording means, and a timing system for controlling a valve in thewater supply for establishing the irrigation interval and energizing onerecording channel to record the duration of the irrigation interval and,at the end of the irrigation interval, to energize the second channel torecord the potential detected by the sensors during a subsequentmeasuring interval.

PATENTEUFEBISIQZI; v 3.563231 INVENTOR BEHRMAN A. DUCOTE LAWRENCE vNICASTRO ATTOR N EY ELECTRONYSTAGMOGRAPH CONTROL SYSTEM This applicationis a continuation of application No. 586,508 filed Oct. 18, 1966 and nowabandoned.

This invention relates to an electronystagmograph, and more particularlyto a system for automatically controlling the irrigation periods and therecording of the effects of irrigation with fluids of selectivelyvariable temperature on the inner ear of a subject.

Electronystagmography is a method of testing individuals for the abilityof the inner ears to detect movement of the fluid therein and for theability of the nerves interconnecting the inner ear and the centralnervous system to relay the stimuli sensed. The tests are helpful todiagnose disorders of equilibrium, both as to location and gravity.Electronystagmograph measurements are based on the fact that irrigatingthe ear canal with a liquid warmer or 'cooler than body temperatureeffects a displacement of the fluid in the inner ear. This causes theeyes repeatedly to move away from and abruptly back to center.Electropotential differences exist between the front and rear of theeyeballs, and small electrical impulses arise when the eyeballs move.Electronystagmographic recordings are made after irrigation by pickingup these impulses with electrodes placed on the surface of the subject'sbody, one at the outer corner of each eye, and one in the middle of theforehead, the latter being used as a reference potential. Suchpotentials are saw-toothed in shape, having a frequency, intensity, andduration that depends on the particular state of the subjects inner earand the nerve interconnections therewith.

The present invention is directed to an improvement in suchoperationswherein control of the irrigation interval and the detectionof the resultant surface potentials are greatly simplified to removemuch of the art from electronystagmography and permit the imposition ofprecise controls thereon.

in accordance with the invention, a supply including a liquid supply ofpredetermined temperature having'a conduit with a control valve thereinand with a nozzle thereon is provided to irrigate the ear of a subject.Detector means are provided for sensing the surface potentials acrosspredetermined points in the region of the patients eyes. A registeringmeans is provided for recording the selected electrical function of thepotentials. Timing means are provided automatically to initiate andterminate fluid flow to the subject's ear for a predetermined irrigationinterval and for actuating the registering means immediately followingthe irrigation interval.

In a further aspect of the invention, means are provided for registeringthe period between the irrigation intervals. In a more specific aspect,first and second timers are provided to suppress as well as facilitateregistration of the amplified potentials across predetermined'pointsadjacent the patients eyes.

For a more complete understanding of the invention and for furtherobjects and advantages thereof, reference may now be had to thefollowing description taken in conjunction with the accompanyingdrawings in which:

The drawing is a schematic diagram of a system embodying the presentinvention.

' minals 29 and 27.

The common emitter terminals 32 of transistors 21 and 22 are connectedto the reference terminal 27 by way of resistor 33. Similarly, thecommon emitter terminals of each of transistors 23 and 24 are connectedto the reference terminal An electronystagmograph embodying the presentinvention I V is shown in the FlG., wherein a subject 10 is fitted withelectrodes 12, 13 and 14, and is also fitted with an irrigation tube 15.ln accordance with electronystagmography, cold water is caused to flowthrough the outer earby means of tube 15. Surface potentials detectedbetween the electrodes 12 and 13 and between electrodes 12 and 14,respectively, are then sensed,

amplified and counted. Such a recording facilitates the study ofdifferent characteristics of nystagmus, for example, duration, speed,amount and intensity. The number of cycles of the detected voltage perunit time over. an extended recovery period following termination of theflow of the cold water pro vides one measure of the sensitivity of theinner ear to liquid flow therein.

In accordance with the invention, a sensitive and optimized amplifiersystem is provided wherein the amplifier 20 comprises three stages ofpush-pull amplification employing low noise transistors. The first stageuses transistors 21 and 22.

27 by way of resistor 34. The collectors of transistors 21 and 22 arecoupled to the base terminals of transistors 23 and 24, respectively, bycapacitors 35 and 35a, respectively. The collector terminals oftransistors 23 and 24 are connected directly to the base terminals oftransistors 25 and 26.

A capacitor 36 is connected in shunt across the base terminals oftransistors 25 and 26. The emitter terminals of transistors 25 and 26are connected to the reference terminal 27 by way of resistors 37 and37a, respectively. The emitters of transistors 25 and 26 are alsocoupled by way of resistors 38 and 39, respectively, to the inputs of asingle ended buffer amplifier 40. Preferably the preamplifier will havea differential input with an impedance greater than 100,000 ohms. Thefrequency response is set so that signals from 1 c.p.s. to 50 c.p.s. areamplified. ln one embodiment, the first two stages combined to give anoverall gain of 50,000 and were followed by an emitter follower with aninput impedance of 2,000 ohms. The common-mode rejection of the inputcircuit was about 50,000 to l. The capacitor serves to filter allunwanted noise and other signals entering the amplifier allowing onlythe desired input signal to pass. Coupling between stages in thepreamplifier with large capacitors, such as capacitors 35 and 350,provides an amplifier with almost DC characteristics and yet gives allthe advantages of an AC coupled circuit with the improved stability ofAC operation.

The output channel from buffer amplifier 40 comprise conductors 41 and42. Conductor 42 is connected directly to a signal input terminal 45bassociated with a recorder system 44. Conductor 41 is further connectedby way of a pair of selected circuits through a pair of relays R1 and R2so that the time intervals during which the signal will effectively beapplied to the signal input terminal 45b may be controlled.

A control system 50 cooperating with amplifier 20 is employedautomatically to program operations on subject 10 with the timeintervals during which each of several operations follow beingselectively variable by manually operable timers. The system functionsto prevent the signals from conductors 41 and 42 from being efiectivelyrecorded in the unit 44 during the time interval that fluid is beingemployed to irrigate the subjects ear, yet provides for recording thetime intervals in which irrigation is continued. On discontinuance ofirrigation, the system then serves to apply the signals from conductors41 and 42 to the recorder to provide an output chart 45 on which boththe irrigation time and the output signals are recorded.

At the same time, signals from conductors 41 and 42 are applied to acounter 46 which may be provided with a suitable tape printout to recordthe number of excursions per unit interval during the period that thesignals are being recorded on the chart 45.

The circuit configuration and the elements employed in the controlsystem 50 will now be described, following which the operation thereofin conjunction with the amplifier 20 will be explained.

The system employs a pair of tanks 51 and 52. Water in tank 51 ismaintained at a temperature of 30 C. Tank 51 thus supplies a cool fluidemployed to irrigate the subjects ear. Tank 52 contains water which ismaintained at a temperature of 44 C and may be employed to irrigate theear of the subject during a different sequence. The precise sequence ofsuch successive operation will depend upon the subject and the operatorand the objectives of the test. In accordance with one mode ofoperation, two cycles of irrigation with the water from tank 51 arecompleted, following which two cycles of irrigation employing water fromthe warm tank 52 are used. Furthermore, a calibration system is providedthat is manually operable by using manual overrides (not shown) andemploys a calibrate signal generator 53.

The control system 50 is supplied with power by way of lines L1 and L2.in the calibration system lines L1 and L2 are connected to the primaryof a stepdown transformer 54. The secondary winding of transformer 54 isconnected by way of conductor 55 to one terminal of two calibrationlights 56 and 57. The other terminals of lights 56 and 57 are connectedto a single pole double throw switch 58. The switch 58 is operated underthe control of a cam 59 which is driven by a motor 60. Motor 60 isenergized by closure of switch S2 which connects the motor 60 directlyacross lines L1 and L2. With switch S2 closed, the motor 60 drives cam59 preferably to turn lights 56 and 57 on and off alternately at onesecond intervals. The subject is then asked initially to follow with hiseyes the actuation of the lights 56 and 57. The lights are mounted atlaterally spaced points. The excursions of the eyes thus produced aresensed and recorded and the system is initially calibrated to secureclearly identified signal levels.

Aside from the foregoing calibration operation, the rest of the systemmay be automatic to provide a preset irrigation interval followed by apreset measuring interval. The operation is carried out through thecombined use of three multichannel relays R1, R2, and R3 and twomanually adjustable timer units TDI and TD2.

One terminal of the coil is relay R1 is connected directly to line L2.The other terminal of relay R1 is connected by way of a foot-actuatedswitch S1 to line L1 Thus, when the foot pedal 65 is depressed, switchS1 is closed and the coil for relay R1 is energized, closing the fourswitches associated therewith. The line 64 from switch S1 and relay R1is also connected to terminal 65 of timer TD2. The switch 66 on relay R1is connected directly to line L1. Switch 67 is connected by way ofswitch S3 to line L2. Switch 68 is connected by way of conductor 73 to afirst switch 70 on relay R2. Switch 69 is connected by way of conductor74 to a second switch 71 on relay R2. The normally opened terminal forswitch 66 is connected by way of conductor 75 to switch 81 of timer TDIand to one terminal of the solenoid 80 of timer TDI, and also to oneterminal of the solenoid 85 of timer TD2 and to the switch 83 of timerTD2.

The normally open terminal of switch 67 is connected by way of conductor86 to the motor 87 which drives the chart in the recorder 45. The otherterminal of motor 87 is connected to line L 1.

The normally closed terminal of switch 68 is connected by way ofconductor 88 to one of the gate terminals 46a on the counter 46. It isalso connected by way of conductor 89 to the normally open terminal ofswitch 70 of relay R2. The second of the counter gate terminals 46a isconnected by way of conductor 90 to conductor 73. Thus, when relay R1 isnot energized, there is a short circuit across the counter gateterminals 46a which prevents the counter from registering. Similarly,when the relay R2 is energized, a short circuit is present by reason ofclosure of switch 70. However, when relay R2 is deenergized and relay R1is energized, there is no short circuit and the signals from lines 41and 42 will register on the counter 46. It will be noted that acapacitor 46d is connected in series with a resistor 46e and that theseries circuit bridges the gate terminals 46a of the counter 46. Theseries circuit provides for transient suppression and eliminates anycount from being accumulated in counter 46 while the fluid is flowmg.

The normally closed terminal of switch 71 is connected by way of line 95to one of the signal input terminals 45a of the recorder 45 and to oneof the signal input terminals 4612 on counter 46.

The normally open terminal of switch 72 is connected by way of line 96and a bias voltage source 97 to one of the mark signal input terminals45b of the recorder 45. The switch 72 is connected to the second of themark signal terminals 45b. When the switch 72 is closed by energizationof relay R2, the voltage from a source, such as battery 97, is appliedto one of the two recorder channels and causes the right-hand pen on therecorder 45 to deflect, thus providing a clear indication of theirrigation time interval.

The time delay control units TDI and TD2 are identical in construction.Unit TDl controls the time interval of fluid flow through channel 15.The timer TD2 controls the total period of time from the start ofirrigation to the end of the testing period.

In the timer TDl, the motor 100 is connected at one terminal to line L2and to one terminal of the relay coil 80. The relay coil controls twoswitches, 81 and 82. The switch 82 is connected to line Ll by way ofconductor 104. When the relay 80 is energized, the switches 81 and 82are actuated to energize the motor and to apply a voltage, by way ofswitch 66, terminal 81 and line 101, to the switch 102 on relay R3. Thetimer operates such that when the preset time interval therein hasexpired, the motor, coupled by way of linkage 105 to the switches 81 and82, returns them to their normally open position.

In timer TD2 power is supplied from line 1 by way of conductor 106andswitch 84 to motor 107. The second terminal of motor 107 is connectedto line L2 by way of line 108. Line 108 is also connected to oneterminal of the relay coil 85. The second coil of relay 85 is connectedbyway of line 109 to switch 83 and to one terminal of relay coil 80 andunit TDI and to switch 81 of unit TDl.

A third relay R3 is provided with switches 102 and 103. As previouslymentioned, power is supplied by way of switch 102 in its open circuitposition and through line 110 to one terminal of a valve solenoid 1 l l.The second terminal of solenoid 111 is coupled by way of line 112 toline L2. It will be remembered, however, that power appears on line 101and at switch 102 only when relay coil 80 and unit TDl is energized. Thesolenoid 111 is coupled by way of linkage 113 to a valve 114 in the flowline leading from the cold water unit 51 to the flow channel 15.

When the solenoid 111 is energized, the valve 114 is actuated to initialflow into the subjects ear. When the solenoid is deenergized, the flowis abruptly terminated. It will be noted that switch 103 in relay R3 iscoupled by way of line 115 to an indicator lamp 116. When lamp 116 isenergized by current flow through switch 103, it will indicate thatrelay R3 is not energized and that any flow in response to actuation ofthe entire system-will be from the cool water tank 51.

Switch S4 leading from line L1 to the coil of relay R3 may be manuallyactuated. When actuated, switches 102 and 103 are moved to condition thesystem for flow from the tank 52 by energizing valve solenoid 117 underthe control of the unit TDl. In the latter case, the indicator light 117will be energized to indicate that any flow in the system will be fromtank 52.

it will be noted that a capacitor is connected to each of the coils orrelays Rl-R3 and in the timers TDI and TD2 for suppression of unwantedtransients in the system during switching operations.

Having described the construction of the system, it will now berecognized that the sequence of operations involves first attaching theelectrodes 10-14 to the subjects brow. Thereafter, the irrigation tube15 is placed in the subjects ear. Calibration procedures employing thecalibration unit 53 may then be initially carried out to makeadjustments as may be necessary to make certain that the electrodes areproperly in place and that noise signals therefrom are at a minimum.

Thereafter, if cold water is to be employed, the switch S4 will beplaced in the open position as illustrated in the FIG. The time intervalduring which the cold water to be circulated is manually set byadjusting the timer TDl. The interval encompassing the irrigation periodas well as the measuring period is then manually set by adjustment ofthe timer TD2.

With the system thus conditioned, the foot switch 65 is depressed,closing switch S1. This promptly closes relay R1. Relay R1 then suppliespower by way of switch 66 to both of the coils 80 and 85 of units TDIand TD2, respectively. Thus, the motors 100 and 107 begin to run. Poweris supplied by way of switchsl to a relay coil of relay R2 and to switch102 to energize the valve solenoid 11 1. At the same time, power fromswitch 66 is applied by way of switch 83 to the second 111 of the relayR1 to hold relay R1 closed so long as the unit TD2 is actuated.

In the foregoing condition, the system remains unchanged throughout theirrigation interval fixed by the timer TDl. So

\ long as the relay R1 is energized, power is supplied by way of switch67 to the motor 87 of the recorder 45, causing the chart to move pastthe pens while the fluid is flowing in the subjects ear. So long as therelay R2 is energized, the battery voltage from the battery 97 isapplied to the marker unit to apply a step function 119 to theright-hand trace on the recorder chart 45c. During the irrigationinterval, switch 71 is open so that no signal can be applied to thesignal terminals 450 of the recorder 45 and terminals 46b of counter 46.

At the end of the irrigation interval, switch 81 opens, deenergizingrelay R2 and, simultaneously, the solenoid 111. When relay R2 isdeenergized, switch 71 returns to its normally closed positioncompleting the signal circuit through switches 69 and 71. Thus, signalsare recorded only at the end of the irrigation interval. The signal 120is shown on the lefthand trace on the recorder chart 45a.

in practice, the timer TDl is set for a preselected interval 7 betweenand 60 seconds. The timer TD2 is set for a combined irrigation andmeasuring interval of up to minutes. Thus. a two trace chart is providedto show not only the times involved but also the waveforms of thereceived signal.

In counter 46 is registered each excursion of the signal on lines 41 and42. The contents of the counter are periodically printed out, and thecounter reset at selectable intervals. A chart 130 having the number ofcounts per unit of time printed thereon thus issues from the counter 46to provide a second record of the performance of the subject.

In one embodiment of the system, the timer units TDI and TD2 were of thetype identified as series MTD automatic reset time delay timersmanufactured and sold by Industrial Timer Corporation of Los Angeles,California. Unit TDl was an MTD-60S unit and TD2 was an MTD-5M unit.

Counter 46 was of the type manufactured and sold by Anadex Instruments,Inc. of Van Nuys, California and identified as Model No. CF-203-4RFrequency Counter with Option 0 l0 second gate time) and Option J (10line printer output).

The recorder was of the type manufactured and sold by Texas InstrumentsIncorporated of Dallas, Texas and identified as Model PlCAH OscilloRiterRecorder.

Having described the invention in connection with certain specificembodiments thereof, it is to be understood that further modificationsmay now suggestthemselves to those skilled in the art and it is intendedto cover such modifications as fall within the scope of the appendedclaims.

We claim:

1. An electronystagmograph wherein a supply of liquid of predeterminedtemperature is provided for irrigating the ear of a subject undercontrol of a valve and wherein electrodes adapted to be attached to thesubject in the region of the subjects eyes measures surface potentialsproduced by movement of the eyes in response to SUChl irrigation, thecombination of which comprises:

a. a low noise, high-gain amplifier responsive to signals in the rangeof from about 1-50 c.p.s. connected at its input to said electrodes andhaving an output channel,

b. a recorder having a signal input terminal,

0. a first relay having associated therewith a normally opened switch,d. a second relay havmg associated therewith a nonnally closed switch,

. an electrical latch system including said normally opened switch andsaid normally closed switch connected in series between said channel andsaid signal input terminal, precision timer means for actuating saidfirst and second relays at the beginning of a desired irrigationinterval and for opening said normally closed switch at the end of saidirrigation interval to apply said signals to said recorder during ameasuring interval following said irrigation interval, and

g. circuit means responsive to said timer means for actuating said valveto initiate flow simultaneously with actuating of said relays and foractuating said valve to terminate said flow simultaneously withdeenergization of said second relay.

2. The combination set forth in claim 1, wherein said supply of liquidincludes a warm subsupply and a cold subsupply, and relay means fordirecting flow of irrigating liquid from said warm subsupply or fromsaid cold subsupply.

3. The combination set forth in claim 1 when said recorder comprising:

a chart recorder,

a counter-printer connected in parallel with said chart recorder andwherein a count inhibiting condition is applied to said counter-printerwhen first relay is deenergized and when said second relay is energized.

4. The combination set forth in claim 3 wherein:

said first relay includes a circuit for applying drive power to saidchart recorder for driving said recorder without interruption throughboth said irrigation interval and said measuring interval.

5. The combination set forth in claim 1 wherein said recorder is a pulsecounter-printer with a repetitive time gate which is short compared withsaid measuring interval and in which the number of excursions duringeach time gate is registered.

'. UNITED S'IA'IES m'rmx'r OFFICE CER'ILIFICA'IE 0F CORRECTION PatentNo. 3,563,231 Dated February 16, 1971 Invcn ofl Behr man A. Ducote, et8.1

It is certified that error appears in the above-identified patent andthat: said Letters Patent are hereby corrected as shown below:

C01. 3, line 32, "is" should read =-1n--; Col. 5, line 10, "111" shouldread --terminal--.

Signed and sealed this '15th day of June 1971.

(SEAL) Attest:

EDWARD WILLIAM E. scuuiLs R, m.

Attesting Officer Commissioner of Patents

1. An electronystagmograph wherein a supply of liquid of predeterminedtemperature is provided for irrigating the ear of a subject undercontrol of a valve and wherein electrodes adapted to be attached to thesubject in the region of the subject''s eyes measures surface potentialsproduced by movement of the eyes in response to such irrigation, thecombination of which comprises: a. a low noise, high-gain amplifierresponsive to signals in the range of from about 1-50 c.p.s. connectedat its input to said electrodes and having an output channel, b. arecorder having a signal input terminal, c. a first relay havingassociated therewith a normally opened switch, d. a second relay havingassociated therewith a normally closed switch, e. an electrical latchsystem including said normally opened switch and said normally closedswitch connected in series between said channel and said signal inputterminal, f. precision timer means for actuating said first and secondrelays at the beginning of a desired irrigation interval and for openingsaid normally closed switch at the end of said irrigation interval toapply said signals to said recorder during a measuring intervalfollowing said irrigation interval, and g. circuit means responsive tosaid timer means for actuating said valve to initiate flowsimultaneously with actuating of said relays and for actuating saidvalve to terminate said flow simultaneously with deenergization of saidsecond relay.
 2. The combination set forth in claim 1, wherein saidsupply of liquid includes a warm subsupply and a cold subsupply, andrelay means for directing flow of irrigating liquid from said warmsubsupply or from said cold subsupply.
 3. The combination set forth inclaim 1 when said recorder comprising: a chart recorder, acounter-printer connected in parallel with said chart recorder andwherein a count inhibiting condition is applied to said counter-printerwhen first relay is deenergized and when said second relay is energized.4. The combination set forth in claim 3 wherein: said first relayincludes a circuit for applying drive power to said chart recorder fordriving said recorder without interruption through both said irrigationinterval and said measuring interval.
 5. The combination set forth inclaim 1 wherein said recorder is a pulse counter-printer with arepetitive time gate which is short compared with said measuringinterval and in which the number of excursions during each time gate isregistered.